Switching fields of magnetic elements with nanometric dimensions have been investigated by Lorentz microscopy using a transmission electron microscope. Acicular elements of Co andNi80Fe20were fabricated by electron beam lithography and lift-off techniques. They were 1.6–3.5 &mgr;m long, 200 nm wide, and 20–50 nm thick, with flat rectangular ends or triangular pointed ends, and were patterned in linear arrays with center-to-center spacing ranging from 7 &mgr;m to 250 nm. Switching fields and reversal behavior of the elements were found to depend strongly on the shape of the ends and, in a closely packed array, on element separation, thereby providing a way of controlling their magnetic properties. ©1997 American Institute of Physics.